1. Field of the Invention
The present invention provides a polythiophene derivative polymer, particularly a polythiophene derivative polymer applied to solar cell.
2. Description of the Prior Art
In recent years, for the application of polymer to solar cell, there are several problems that have to be improved, such as insufficient light absorption range, shorter wavelength of adsorbed light (only about 700 nm), low charge transferring speed, and easy recombination phenomenon and so on.
Thus, there are many research results about the improvement of solar cell efficiency have been published in recent years. It means to use different annealing temperature and different time to reduce the resistance of components, or introduce the electrode having low work function as the technological means. On the other hand, there are few researches that discuss the introduction of different conjugated monomers to change the structure of polymer.
As for the polymerization of donor-acceptor polymer, for example, there is significant progress for the addition of polyfluorene on the main chain. The introduction of polyfluorene can change the highest occupied molecular orbital (HOMO) energy level but reduce electron mobility and hole mobility. Therefore the new introduced material can improve the electron and hole mobility and the efficiency.
Obviously, under the circumstance that the existing technology is unable to reach effective light absorption and charge transferring, it is more important for the research and development of the advanced material to the solar cell technology.